Increasing Yield and Carbon Sequestration of Hemp Production with Understory Companion Crops

Project Overview

Project Type: Partnership
Funds awarded in 2019: $20,224.00
Projected End Date: 05/31/2021
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Project Leader:
Dr. Eric Bishop-von Wettberg
University of Vermont

Information Products


  • Agronomic: clovers, hemp


  • Crop Production: cover crops, strip tillage
  • Education and Training: on-farm/ranch research
  • Farm Business Management: budgets/cost and returns
  • Natural Resources/Environment: carbon sequestration
  • Pest Management: competition
  • Soil Management: nutrient mineralization, organic matter, soil quality/health

    Proposal abstract:

    The 2018 Farm Bill and state-level initiatives have facilitated rapidly expanding hemp production in many northeastern states, creating an economic opportunity for farmers and value-added producers. However, this intensification of production could lead to increased run-off, nutrient loss, and soil degradation on hemp farms. Because of the complex legal history of hemp, management practices for maintaining soil health have received limited research.  Research comparing the impacts of ground covering plastic to undersown crops, particularly nitrogen-fixing legumes, can shed light on the benefits and costs of management decisions. Research on the various effects of farming methods on yield, soil health, nutrient management and carbon sequestration is needed to support farm management decisions. We will examine different undersown crops including two species of clover, fenugreek, and mixed sowings, and compare them to black plastic and no ground cover treatments. We will compare soil nitrogen and carbon across treatments, as well as weed pressure, and the cost of materials. We will also calculate the potential value of carbon credits with different treatments, to provide information to allow farmers to earn credits as markets for carbon reduction mature and expand. We hypothesize that if an understory companion crop can be successfully established below the hemp, the companion crop will effectively provide weed management (eliminating the need for petrol based plastic mulches), have no negative effects on yield or labor, and sequester more carbon per square foot when compared to plots that have plastic mulch, no mulch, or traditional wood-based mulches.

    Project objectives from proposal:

    Our objective is to examine different methods of ground management in hemp farming. Our experimental planting will determine if procumbent forage crops like white and red clover or fenugreek can suppress weeds, provide soil nitrogen, sequester carbon and reduce erosion, at a price comparable to black plastic. By calculating input costs, we will model the expected monetary and environmental costs of different cultivation approaches to provide information for the growing number of hemp farmers in the Northeast.

    We will also record carbon capture data on the plots so that we will be able to identify and quantify the varying rates of carbon sequestered under each treatment regime. There is growing national and international interest in carbon sequestration, and hemp is among the most effective annual crops at sequestering carbon (Finnan and Doyle, 2013). If coupled with low input production approaches such as co-planting with forage legumes, carbon offset credits from existing carbon markets such as those in California or Quebec, or new ones in the US, are possible.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.